Multiple fill compacting press

ABSTRACT

A five-stage compacting press having independently adjustable stages is disclosed for making multilayered laminated objects from powdered materials.

United States Patent Kopicko MULTIPLE FILL COMPACTING PRESS Inventor: Walter J. Kopicko, Wilmington,

Del.

Assignee: Baldwin-Hamil on p y Wilmington, Del.

Filed: Nov. 16, 1970 Appl. No.: 89,786

US. Cl. ..425/352, 425/78, 425/344 Int. CL ..B30b ll/02 Field oISearcll ..l8/l6 R, 16.5, 16.7, 17 S,

[151 3,690,805 51 Sept. 12,1972

[56] References Cited UNITED STATES PATENTS 2,640,325 6/1953 Haller ..l8/ 16.5 X 3,379,043 4/1968 Fuchs ..l8/ 16 R X 2,137,986 11/1938 Sanford ..l8/36 X 2,407,123 9/1946 Allison 18/16 R Primary Examiner-J. Howard Flint, Jr. Attorney-Seidel, Gonda & Goldhammer [57] ABSTRACT A five-stage compacting press having independently adjustable stages is disclosed for making multilayered laminated objects from powdered materials.

15 Claims, 5 Drawing Figures Patented Sept. 12, 1972 3,690,805

4 Sheets-Sheet 1 2 nv vs/v 70R WALTER J. xo /c/ro ATTORNEYS FIG. IA

Patonted Sept. 12, 1912 3,690,805

4 Sheets-Sheet 4 INVENTOR WALTER J. KOP/CKO ATTORNEYS MULTIPLE FILL COMPACTING PRESS This invention is directed to a multiple fill compacting press having a plurality of independently adjustable stages. For purposes of disclosure, the press will have five such stages. Depending upon the numbers of layers in the object to be compacted from powdered material, all of the stages need not be utilized simultaneously. Thus, the press of the present invention may be operated in a manner comparable to a three-stage press, four-stage press, etc. The press may be manually operated, it may be semi-automatic, or may be automatically operated.

Each of the stages of the press is comprised of coaxial piston-cylinder arrangements. Each piston has a cylinder portion reciprocably receiving the piston thereabove. Each cylinder portion has means for adjusting the length thereof to act as a limit stop for the piston thereabove.

A compacting press in accordance with the present invention facilitates producing multilayer grinding wheels from powdered material with each layer being internally reinforced by a layer of reinforced type material. The stages of the press are structurally interrelated in a manner so as to be compact with the means for facilitating stroke adjustment of each stage being located at the stage for ease of adjustment by an operator. A common cylinder rod is provided for controlling movement of each piston to its rest position.

Circuitry associated with the first stage of the press of the present invention provides for float action which is sometimes called opposed action. In such float action, the lower punch descends under ram pressure until it bottoms out, thereby providing a dense compaction on the bottom surface of the object being produced. After the lower punch bottoms out, continued ram pressure similarly compacts the top surface portion of the object being produced to thereby pro vide a dense compaction of the same.

It is an object of the present invention to provide a novel multiple fill compacting press.

It is another object of the present invention to provide a compacting press having a plurality of independent adjustable piston-cylinder stages.

, It is another object of the present invention to provide a multiple fill compacting press capable of producing laminated multilayer grinding wheels from powdered material.

It is another object of the present invention to provide a compacting press having a plurality of compact stages, each of which has a stroke adjustment.

It is another object of the present invention to provide a multiple fill compacting press having a plurality of compact adjustable stages which facilitates producing sintered non-metallic or metallic objects having up to five fill stages, with or without internal reinforcement.

It is another object of this invention to provide a multiple fill compacting press wherein fill volume and ejection position are accurately established by the mechanical dimensions of the various stages.

It is another object of the present invention to provide a multiple fill compacting press wherein a common control piston serves to return all stages to their rest positions.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. a

FIG. 1A is a side elevation view, partly in section, of the press of the present invention.

FIGS. 18 and 1C diagrammatically illustrate hydraulic circuitry for the press shown in FIG. 1.

FIG. 2 is a vertical sectional view of the-adjustable stages of the compacting press shown in FIG. 1 but on an enlarged scale.

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 2.

Referring to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIG. I a multiple fill compacting press in accordance with the present invention designated generally as 10.

The press 10 includes a base 12 mounted on legs 14. The base 12 is provided with upstanding posts 16 and 18. A die head 20 is supported by the posts 16 and 18 intermediate their ends. A bridge 22 is at the upper ends of the posts 16 and 18.

A hydraulic cylinder 24 is supported by the bridge 22. A piston 26 within the cylinder 24 is provided with a piston rod 28. A ram 30 is adjustably connected to the piston rod 28 and by the piston rod 28 is caused to move toward and away'from the die head 20. A guide plate 23 slidably engages the posts 16 and 18 to guide movement of the piston rod 28.

A removable die in the form of a ring 32 is supported in an opening in the die head 20. The inner periphery of the die ring 32 defines the die orifice. Guide rods 34 and 36 are threadedly coupled to the lower surface of the die head 20. A ram plate 38 is slidably guided for movement toward and away'from the die head 20 by the guide rods 34 and 36.

A lower punch 40 is removably coupled to the upper surface of the ram plate 38 by means of bolts extending through a radially outwardly directed flange on the punch 40. The ram plate 38 rests on a fifth pistoncylinder stage 42. Fifth stage 42 is supported by a fourth stage 44 which in turn is supported by a third stage 46. The third stage 46 is supported by a second stage 48 which in turn is supported by a first stage 50.

The fifth stage 42 includes a piston 52 reciprocably supported within a cylinder portion 54 of a piston 56 therebelow. A cylindrical cap 58 is threaded to the outer periphery of position 54 and has an inwardly directed flange in sealing contact with a reduced diameter portion of the piston 52 and acts as a limit stop for the upward movement of piston 52 due to contact with a shoulder on the piston 52. Motive fluid such as a hydraulic oil is introduced and removed from the chamber below piston 52 by way of a supply and exhaust conduit 60 and an axial passage in piston 56.

The piston 56 is part of a fourth stage 44 and is reciprocably supported within the cylinder portion 62 of a piston 64. Piston 64 is below piston 56 and coaxial with pistons 52 and 56. A cylindrical cap 66 is threadedly coupled to the outer periphery of the cylinder portion 62. Cap 66 has an inwardly directed flange in sealing contact with a reduced diameter portion of piston 56 and acts as a limit stop for the upward movement of piston 56 due to contact with a shoulder on the piston 56. Motive fluid such as a hydraulic oil is introduced and removed from chamber 70 below piston 56 by supply and exhaust conduit 68. Guide pins 72 on piston 64 prevent piston 56 from rotating relative to piston 64.

The third stage piston 64 is reciprocably supported within a cylinder portion 76 of a piston 74 therebelow. A cylindrical cap 78 is threadedly coupled to the outer periphery of postion 76 and has an inwardly directed flange in sealing contact with a reduced diameter portion of the piston 64 and acts as a limit stop for the upward movement of piston 64 due to contact with a shoulder on the piston 64. Motive fluid such as a hydraulic oil is introduced and removed from the chamber 80 below piston 64 by way of a supply and exhaust conduit 82 and an axial passage in piston 74. Guide pins 81 on piston 74 prevent piston 64 from rotating relative to piston 74.

The piston 74 is part of second stage 48 and is reciprocably supported within the cylinder portion 84 of a piston 86. Piston 86 is below piston 74 and coaxial with pistons 52, 56 and 64. A cylindrical cap 88 is threadedly coupled to the outer periphery of the cylinder portion 84. Cap 88 has an inwardly directed flange in sealing contact with a reduced diameter portion of the piston 74 and acts as a limit stop for the upward movement of piston 74 due to contact with a shoulder on the piston 74. Motive fluid such as a hydraulic oil is introduced and removed from the chamber 90 below piston 74 by way of a supply and exhaust conduit 92 and an axial passage in piston 74. Guide pins 94 on piston 86 prevent piston 74 from rotating relative to piston 86.

The piston 86 is part of a first stage 50 and is reciprocably supported within the cylinder portion 96 of a cylinder 98. Cylinder 98 is below piston 86 and coaxial with piston 86. A cylindrical cap 100 is threadedly coupled to the outer periphery of the cylinder portion 96. Cap 100 has an inwardly directed flange in sealing contact with a reduced diameter portion of the piston 86 and acts as a limit stop for the upward movement of piston 86. Motive fluid such as a hydraulic oil is introduced and removed from the chamber 102 below piston 86 by way of a supply and exhaust conduit 104 and an axial passage in cylinder 98. Guide pins 106 on cylinder 98 prevent piston 86 from rotating relative to cylinder 98.

Each of the caps 58, 66, 78, 88 and 100 have wrench holes on their outer periphery to facilitate adjustment with respect to their cylinder portion. The caps are each provided with a set screw to hold the caps in any set position on their respective cylinder portions. Each of the pistons 56, 64, 74 and 86 have a recess on their lower surface to receive one of the guide pins 72, 81, 94 and 106. Each guide pin is slightly smaller in diameter than its respective recess. It will be noted that the diameter of the pistons increase in a direction away from the die head 20. That is, piston 86 is larger in diameter than any piston thereabove, piston 74 is larger in diameter than any piston thereabove, etc.

Plate 38 and each piston has a central bore. The central bore in each piston is in sealing reciprocal contact with a rod 108. It will be noted that the sealing contact between the pistons and the rod 108 is for a distance substantially smaller than one half the thickness of the pistons in an axial direction. Rod 108 at its upper end has an extension 110. Extension 110 terminates in head 112. Head 112 overlies a shoulder around the bore in plate 38 so that downward movement of rod 108 causes downward movement of plate 38 which in turn applies a downward force to each of the pistons.

The lower end of rod 108 is threadedly coupled to the piston 114 which is disposed in chamber 116. The chamber 116 is within the cylinder 98. Rod 108 extends through a bore at one end of chamber 116. A cover 118 removably connected to the cylinder 98 closes the other end of the chamber 116. A supply and exhaust conduit 120 communicates with the space above piston 114 in chamber 116. A conduit 122 continuously vents chamber 116 below piston 114 with a tank return 124.

Cylinder 98 is removably secured to the inner periphery of a sleeve 126 in any convenient manner such as by set screws. A pair of keys 128 are secured to the outer periphery of sleeve 126, with each key riding in a vertically disposed slot 130. The outer periphery of sleeve 126 is threadedly coupled to the inner periphery of a gear 132.

The gear 132 has an axially disposed shank resting on a pressure plate 134. Plate 134 is supported by the base 12. A cylindrical bushing 136 surrounds the outer periphery of the shank portion of the gear 132. Gear 132 meshes with a smaller gear 138 keyed to a shaft 140. Shaft 140 terminates at its upper end in a wrench head 142. A cover plate 144 is removably secured to the base 12 in overlying relationship with respect to the gears 132 and 138. The shaft 140 is suitably journaled in the base 12 and provided with bushings. A bearing 146 is disposed above the plate 144 and acts as a suitable guide for rotation of shaft 140. As shaft 140 rotates, gear 138 rotates gear 132. As gear 132 rotates, it causes the sleeve 126 to move in a vertical direction without rotating and in doing so moves the entire five stages toward or away from the die plate 20.

Motive fluid such as hydraulic oil is communicated to the cylinder 24, see FIG. 1A, by supply and exhaust conduits 148 and 150. Conduit 148 communicates with the pump or other source of pressurized fluid 154 and contains a four-way double acting solenoid value 152. Conduit 150 similarly communicates with a pump 156, with conduit 150 containing a four-way solenoid operated valve 160. The pumps 154 and 156 communicate with the supply tank 158.

As shown more clearly in FIG. 1C, conduit 150 com municates with tank return 162 by way of conduit 164 and the valve 152. Conduit 148 communicates with tank return 168 by way of conduit 166, valve 160, and conduit 170. Each of the valves are in a neutral position. When valve 152 is activated so as to move upwardly to a position where pump 154 communicates with conduit 148, valve likewise is moved upwardly so that conduit 166 communicates with the outlet side of pump 156. In the position shown in FIG. 1C, the output of pump 154 communicates with the tank return 162.

When the valve 152 moves downwardly from the neutral position shown in FIG. 1C, the output of pump 154 communicates with conduit 150 by way of conduit 164. At the same time, conduit 148 communicates with the tank return 162. At the same time, the valve 160 moves downwardly from the neutral position shown in FIG. 1C so that conduit 166 communicates conduit 148 with conduit 170 and the tank return 168. Simultaneously, conduit 150 communicates with pump 156.

A hopper 174 for the material to be compacted in the die cavity is reciprocably supported on the upper surface of the die head 20. The hopper 174 is cyclically reciprocated so as to overlie the die cavity by means of a piston rod 176. Piston rod 176 is connected to a piston 180 within cylinder 178. Motive fluid such as a hydraulic oil is supplied to opposite ends of the cylinder 178 by conduits 182 and 184. See FIG. 1A.

Referring to FIG. 1C, it will be noted that the conduits 182 and 184 are alternatively coupled to supply conduit 172 or a tank return 186. Conduit 182 communicates with the outlet of pump 156. A four-way solenoid operated valve 188 is coupled across conduits 182 and 184 whereby the conduits 182 and 184 are alternatively connected to supply or exhaust. Conduit 182 is provided with a variable restrictor 190 and conduit 184 is provided with a similar variable restrictor 192. The restrictors control the rate at which the piston 180 may be moved.

Referring to FIGS. 13 and 2, it will be noted that the supply and exhaust conduits 60, 68, 82 and 92 each communicate with the supply conduit 172 or with a tank return. Thus, conduit 60 communicates with conduit 172 or tank return 196 by way of a control valve assembly 194. Likewise, conduit 68 is provided with a similar control valve assembly 198, conduit 82 is provided with a similar control valve assembly 200, and conduit 92 is provided with a similar control valve assembly 202.

Each of the control valve assemblies is identical. Hence, only control valve assembly 194 will be described in detail. The control valve assembly 194 includes a pressure regulator 204 having means for providing a constant outlet pressure which is readable on the gauge 206. The assembly also includes a fourway control solenoid operated valve 208. Valve 208 alternately couples conduit 60 with either the conduit 172 or the tank return 196.

Referring to FIG. 13, it will be noted that conduit 120 communicates directly with conduit 172 by way of a constant outlet pressure regulator 210. Conduit 104 communicates with conduit 172 or tank return 212 by way of a variable restrictor 214 andvalve assembly 216.

The valve assembly 216 includes a four-way solenoid operated valve 218 which communicates with conduit 172 by way of a pilot-operated valve 220. The pilot valve 220 is operated by the pressure in pilot conduit 222 containing a check valve 224. The pressure in conduit 222 is a function of the position of the vent valve 228. Vent valve 228 is provided in conduit 226 and interconnects the conduit 104 with the tank return 230. As the pressure in conduit 226 builds up to a point whereby it opens valve 228 and communicates conduit 226 with the tank return 230, the pressure in conduit 222 is likewise increased. At the point where vent valve 228 is open, the pressure in conduit 222 reaches a point whereby it prevents operation of the pilot valve 220.

Conduit 222 may be selectively communicated with a tank return 232 by means of a solenoid operated fourway valve 234 and one of a high pressure vent valve 236 or a low pressure vent valve 238. See FIG. 1B. The valves 234, 236 and 238 prevent overloading of the pressure in conduit 222 and facilitate the provision of hydraulic resistance to the downward movement of the ram 30 whereby a dense shell will be provided on opposite sides of the object to be produced on the press 10. This is referred to above as float action or opposed action.

The press 10 of the present invention is utilized as follows: The press of the present invention may be operated in any one of three modes of operation, namely manual, semiautomatic, and automatic.

SEMIAUTOMATIC OPERATION The press 10 must be in the ready position. This is accomplished manually. The ram' 30 is placed in the operative position by energizing the solenoid of valve and the uppermost solenoid on valve 152. This is accomplished by means of the main ram up-down selector switch. The main ram 30 now moves up and contacts an upper limit switch and stops. The main ram 30 is now in the ready position.

The hopper 174 is in the inoperative position shown in FIG. 1A. This is the normal position for the hopper 174. Piston 86 is in its lowermost disposition since chamber 102 communicates directly with the tank return 212 by way of conduit 104 and valve 218 which assumes the normal position illustrated in FIG. 1B. The pistons of stages 42, 44, 46 and 48 are in their up position. This is accomplished by turning the respective selector switches to the up position, thereby energizing the solenoids of valve 208 and the corresponding valves forming a part of the control valve assemblies 198, 200 and 202. As shown in FIG. 13, valve 208 is in an inoperative position and moves downwardly against the action of the spring when activated so as to enable hydraulic fluid under pressure to flow from conduit 172 to conduit 60.

The press 10 is now ready for semiautomatic operation. Five fills will be used in this explanation of the sequence of operation. It is to be noted that the first drop for a fill is accomplished with the lowermost of the stages whereas the last fill is accomplished with the uppermost stage. The fill selector switch is set at 5. This selector switch is capable of selecting from one to five fills.

An operator places a layer of reinforced cloth in position in the die cavity. The operator now depresses two palm pushbuttons located on each side of the press. The use of two palm pushbuttons is per se old in the press art and constitutes a safety feature. This initiates the movement of hopper 174 by energizing the solenoid on valve 188 to a position wherein the righthand end of cylinder 178 communicates with conduit 172 by way of conduit 184 and the righthand end of conduit 182.

As the hopper 174 reaches a position wherein it overlies the die cavity, powdered material fills the die cavity and a limit switch is tripped which deenergizes the solenoid on valve 188, thereby returning the hopper to its normal position as shown in FIG. 1A. As the hopper 174 moves toward the positionshown in FIG. 1A, it contacts an adjustable limit switch which initiates the second drop for fill by deenergizing the solenoid for the valve in the valve control assembly 202. As

a result thereof, conduit 92 now communicates with the tank return, whereby piston 74 descends to its lowermost position.

The press cycle now stops and the operator will place an additional layer of reinforced material in the die cavity. The operator will now again depress the palm pushbuttons for the movement of the hopper 174. This procedure is followed until the solenoids for the valves in the valve control assemblies 200, 198, and 194 have been deenergized, thus completing all fills in a five-fill sequence.

At the end of the fifth fill, as the hopper 174 is returning, it will contact a main ram advanced limit switch.

The main ram 30 will then be signalled for advance. However, the main ram 30 will not actually advance until the operator has placed the last reinforced layer of cloth in place and again places each hand on the palm pushbuttons. This will complete the circuit.

At this point, the lowermost solenoid on valve 152 and the lowermost solenoid on valve 160 are energized. The ram 30 rapidly advances until an adjustable slowdown limit switch is contacted. Then the main ram 30 operates at a pressing speed with deenergizing of the lowermost solenoid on valve 160. The main ram 30 continues at pressing speed until the object has been fully compressed, at which point the main ram 30 contacts a limit switch which starts an adjustable timer. The timer will introduce a dwell in the cycle for approximately one-half second to assure that the main ram 30 has bottomed against an adjustable mechanical stop.

When the timer times out, the main ram 30 is moved upwardly. The uppermost solenoid on valve 152 is deenergized so that the space above piston 26 may communicate by way of conduit 148 with the tank return 162.

Midway through its return upstroke, the main ram 30 contacts an ejection sequence limit switch which deenergizes the upper solenoid of valve 160 and energizes the solenoid of valve 218 as well as the solenoids of the valves in the control valve assemblies 194, 198, 200 and 202. As a result thereof, the object produced is ejected from the die cavity as the main ram 30 is returning to its uppermost position as shown in FIG. 1A.

After the object has been fully ejected, and the ram plate 38 contacts an up limit switch, a timer starts. When this timer times out, the solenoid of valve 218 is deenergized and the first stage drops or falls. At the same time, the upper solenoid of valve 160 is energized. As described above, the main ram 30 is returning while the object is being ejected. At the end of ejection, the object is transferred and a timer times out.

AUTOMATIC CYCLE The press 10 must be in the ready position as was justed height of the sleeve 126.

described above in connection with semiautomatic operation. The pistons of stages 42, 44 and 46 must in their uppermost position. This is done by manual selector switches for the respective stages. The operator depresses the run pushbutton. This energizes the solenoid on valve 188 causing the hopper 174 to move to a position wherein it overlies the die cavity. As the hopper 174 moves in and begins to cover the die cavity,

a fill sequence limit switch is contacted deenergizing the solenoid of valve 218 and the solenoids in the control valve assemblies 200 and 202. Pistons 86, 64 and 64 are now in their lowermost position. When the hopper 174 overlies the die cavity, it will contact a limit switch which deenergizes the solenoid on valve 188 whereby the hopper 174 will return to its normal position.

As the hopper 174 moves to the right in FIG. 1A, it contacts a main ram advance limit switch which energizes the lowermost solenoid of valve 152 and the lowermost solenoid of valve 160. The main ram 30 is now in rapid advance and will advance until a slowdown switch is tripped. The sequence for pressing is the same as described above under semiautomatic cycling.

When the main ram 30 returns and contacts the ejection sequence limit switch, the solenoid of valve 218 and the solenoids of the valves in the control valve assemblies 200 and 202 are energized to start the ejection cycle. After the object has been fully ejected, and the ram plate 38 contacts the up limit switch, the solenoid of valve 188 is energized and the hopper 174 commences to move toward the die cavity. Thereafter, the cycle is repeated.

A variety of different objects may be produced by the present invention, one such object being a multilayer internally reinforced grinding wheel made from powdered grinding wheel material.

The concave loop portion of the conduits 60, 68, 82, 92, 104, and 122 in FIG. 1A represents a flexible portion so that the pistons in the stages 42-50 may move up and down.

In the presently preferred form of the press 10, the conduit 120 constantly supplies oil under pressure to chamber 116 thereby applying a constant downward bias on piston 114 and rod 108. The bias applied to rod 108 is transmitted to plate 38 and the pistons of the five stages. Fluid pressure applied to any of the stage pistons must be sufficiently high to overcome this downward bias. When the chamber below any stage piston is vented to a tank return, the downward bias on the rod 108 moves the piston downwardly, thereby expelling the fluid therebelow. Since the solenoid valve in the control valve assemblies 194, 198, 200 and 208 and valve 218 have a normal position wherein the piston chamber communicates with the tank return, see FIG. 1B, the pistons in the five stages are biased to an inoperative or down position.

The rest position of the punch 40, and therefore the fill volume of the cavity defined by the die ring 32, are determined by the fixed mechanical dimensions of the parts forming the five stages, and by the adjusted height of the sleeve 126. The portion of the adjusted punch 40 at ejection is accurately determined by the dimensions of the pistons 52, 56, 64, 74, 86, the adjusted positions of the cylindrical caps 58, 66, 78, 88, 100, and the ad- The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

I claim:

l. A multiple fill compacting press comprising a die having a die cavity, a ram mounted for movement toward and away from the die, a punch on the opposite side of the die with respect to the ram, a multiple stage means for selectively moving the punch axially with respect to the die cavity in incremental stages away from the ram, said means including coaxial first and second pistons, said first piston having a cylinder portion integral therewith, said second piston being reciprocably sealed with respect to said cylinder portion on the first piston, adjustable means on said cylinder portion of the first piston to limit the stroke of said second piston, and biasing means coupled to said pistons for biasing said pistons in a direction away from the ram to their rest positions.

2. A press in accordance with claim 1 wherein said biasing means is secured to said second piston to bias said second and said first pistons to their respective rest positions.

3. A press in accordance with claim 1 including third and fourth pistons coaxial with said first-mentioned pistons, said fourth piston being reciprocably sealed with respect to a cylinder portion on the third piston, adjustable means on the cylinder portion on the third piston, adjustable means on the cylinder portion of said third piston to limit the stroke of said fourth piston, said third piston being reciprocably sealed with respect to a cylinder portion on the second piston, adjustable means on the cylinder portion of the second piston for limiting the stroke of said third piston, and said biasing means being coupled to said third and fourth pistons.

4. A press in accordance with claim 3 wherein said biasing means is secured to said fourth piston to bias said fourth piston and the other pistons to their respective rest positions.

5. A press in accordance with claim 3 including a hopper mounted for repetitive movement from an inoperative position to a position wherein it overlies the die cavity, said multistage means including circuitry for selectively moving at least one of said pistons in an axial direction away from the die cavity after each movement of the hopper from a position overlying the die cavity to the inoperative position of the hopper.

6. A press in accordance with claim 3 wherein said pistons are disposed one above the other and below the die cavity, and means for introducing pressurized fluid through said second piston to a chamber below said second piston and to a chamber below said first piston to effect movement of said first and second pistons with respect to said die cavity.

7. A press in accordance with claim 6 including means extending between said fourth and third pistons to prevent relative rotation, means extending between said third and second pistons to prevent relative rotation, and said punch being mounted on a plate, and guide members cooperating with said plate to guide said plate for movement in a direction corresponding to the longitudinal axis of said pistons.

8. A press in accordance with claim 3 including a ram plate coupled to said fourth piston, said biasing means comprising a rod extending through said pistons and coupled to said ram plate, and means for applying a bias on said rod for transmission to said plate and pistons tending to move said from said die cavity.

9. A press in accordance with claim 8, including mechanical means for moving said rod and each of said pistons as a unit toward and away from said die cavity.

10. A press in accordance with claim 1 wherein said adjustable means includes a cap threadedly coupled to the outer periphery of said cylinder portion, said cap having an inwardly directed flange in sealing contact with said first piston.

11. A multistage compacting press comprising a ram mounted for upright movement toward and away from a die having a die cavity, a hopper mounted for movement from an inoperative position to a position where it overlies the die cavity, a punch below said die cavity, a multistage means coupled to the punch for moving the punch into and out of the die cavity in incremental stages, said multistage means including a plurality of coaxial pistons, most of said pistons being reciprocably sealed with respect to a cylinder portion on the piston therebelow, adjustable means on each cylinder portion to limit the stroke of the piston thereabove, means including a rod coupled to said uppermost piston for applying a constant fluid pressure bias on said pistons tending to move said pistons downwardly away from said die cavity, and valved conduit means coupled to the cylinder portions for selectively introducing a pressurized fluid into the cylinder portions to move the pistons upwardly against and to overcome said bias.

12. A press in accordance with claim 11 wherein each piston has a diameter greater than the diameter of the piston thereabove, and said rod extending through said pistons in an axial direction.

13. A multistage press comprising a die having a die cavity, a ram mounted for movement toward and away from the die, a punch on the opposite side of the die with respect to the ram, said punch coupled to a multistage means for incrementally moving the punch in stages, said means including first, second, and third coaxial pistons, said second and third pistons having integral cylindrical portions, said first piston being reciprocably sealed with respect a cylinder portion on the second piston, adjustable means on said second piston cylinder portion to limit the stroke of said first piston, said second piston being reciprocably sealed with respect to the third piston cylinder portion, adjustable means on the third piston cylinder portion to limit the stroke of said second piston, and means for applying a fluid pressure bias on one of the pistons to bias the pistons in an axial direction.

14. A press in accordance with claim 13 wherein said last-mentioned means includes a cylinder, a fourth piston in said cylinder, a rod connected to said fourth piston, said rod extending through each of the first, second and third pistons, a base supporting said cylinder, and mechanical means for moving said cylinder and said pistons as a unit in an axial direction with respect to said base.

15. A press in accordance with claim 14 wherein each adjustable means on the cylinder portions is a cap threaded to the outer periphery of the cylinder portions.

plate and pistons away 

1. A multiple fill compacting press comprising a die having a die cavity, a ram mounted for movement toward and away from the die, a punch on the opposite side of the die with respect to the ram, a multiple stage means for selectively moving the punch axially with respect to the die cavity in incremental stages away from the ram, said means including coaxial first and second pistons, said first piston having a cylinder portion integral therewith, said second piston being reciprocably sealed with respect to said cylinder portion on the first piston, adjustable means on said cylinder portion of the first piston to limit the stroke of said second piston, and biasing means coupled to said pistons for biasing said pistons in a direction away from the ram to their rest positions.
 2. A press in accordance with claim 1 wherein said biasing means is secured to said second piston to bias said second and said first pistons to their respective rest positions.
 3. A press in accordance with claim 1 including third and fourth pistons coaxial with said first-mentioned pistons, said fourth piston being reciprocably sealed with respect to a cylinder portion on the third piston, adjustable means on the cylinder pOrtion on the third piston, adjustable means on the cylinder portion of said third piston to limit the stroke of said fourth piston, said third piston being reciprocably sealed with respect to a cylinder portion on the second piston, adjustable means on the cylinder portion of the second piston for limiting the stroke of said third piston, and said biasing means being coupled to said third and fourth pistons.
 4. A press in accordance with claim 3 wherein said biasing means is secured to said fourth piston to bias said fourth piston and the other pistons to their respective rest positions.
 5. A press in accordance with claim 3 including a hopper mounted for repetitive movement from an inoperative position to a position wherein it overlies the die cavity, said multistage means including circuitry for selectively moving at least one of said pistons in an axial direction away from the die cavity after each movement of the hopper from a position overlying the die cavity to the inoperative position of the hopper.
 6. A press in accordance with claim 3 wherein said pistons are disposed one above the other and below the die cavity, and means for introducing pressurized fluid through said second piston to a chamber below said second piston and to a chamber below said first piston to effect movement of said first and second pistons with respect to said die cavity.
 7. A press in accordance with claim 6 including means extending between said fourth and third pistons to prevent relative rotation, means extending between said third and second pistons to prevent relative rotation, and said punch being mounted on a plate, and guide members cooperating with said plate to guide said plate for movement in a direction corresponding to the longitudinal axis of said pistons.
 8. A press in accordance with claim 3 including a ram plate coupled to said fourth piston, said biasing means comprising a rod extending through said pistons and coupled to said ram plate, and means for applying a bias on said rod for transmission to said plate and pistons tending to move said plate and pistons away from said die cavity.
 9. A press in accordance with claim 8, including mechanical means for moving said rod and each of said pistons as a unit toward and away from said die cavity.
 10. A press in accordance with claim 1 wherein said adjustable means includes a cap threadedly coupled to the outer periphery of said cylinder portion, said cap having an inwardly directed flange in sealing contact with said first piston.
 11. A multistage compacting press comprising a ram mounted for upright movement toward and away from a die having a die cavity, a hopper mounted for movement from an inoperative position to a position where it overlies the die cavity, a punch below said die cavity, a multistage means coupled to the punch for moving the punch into and out of the die cavity in incremental stages, said multistage means including a plurality of coaxial pistons, most of said pistons being reciprocably sealed with respect to a cylinder portion on the piston therebelow, adjustable means on each cylinder portion to limit the stroke of the piston thereabove, means including a rod coupled to said uppermost piston for applying a constant fluid pressure bias on said pistons tending to move said pistons downwardly away from said die cavity, and valved conduit means coupled to the cylinder portions for selectively introducing a pressurized fluid into the cylinder portions to move the pistons upwardly against and to overcome said bias.
 12. A press in accordance with claim 11 wherein each piston has a diameter greater than the diameter of the piston thereabove, and said rod extending through said pistons in an axial direction.
 13. A multistage press comprising a die having a die cavity, a ram mounted for movement toward and away from the die, a punch on the opposite side of the die with respect to the ram, said punch coupled to a multistage means for incrementally moving the punch in stages, said means including First, second, and third coaxial pistons, said second and third pistons having integral cylindrical portions, said first piston being reciprocably sealed with respect a cylinder portion on the second piston, adjustable means on said second piston cylinder portion to limit the stroke of said first piston, said second piston being reciprocably sealed with respect to the third piston cylinder portion, adjustable means on the third piston cylinder portion to limit the stroke of said second piston, and means for applying a fluid pressure bias on one of the pistons to bias the pistons in an axial direction.
 14. A press in accordance with claim 13 wherein said last-mentioned means includes a cylinder, a fourth piston in said cylinder, a rod connected to said fourth piston, said rod extending through each of the first, second and third pistons, a base supporting said cylinder, and mechanical means for moving said cylinder and said pistons as a unit in an axial direction with respect to said base.
 15. A press in accordance with claim 14 wherein each adjustable means on the cylinder portions is a cap threaded to the outer periphery of the cylinder portions. 